International Journal of Horticulture, 2025, Vol.15, No.1, 8-20 http://hortherbpublisher.com/index.php/ijh 17 Figure 4 Schematic representation of sugar and organic acid metabolites during fruit developmental stages in two yellow-peel pitayas. Phe: phenolic; Fla: flavonoid; AA: ascorbic acid; Glu: glucose; Suc: sucrose; Fru: fructose; Gal: galactose; Ino: inositol; Sor: sorbitol; Mal: malic; Cit: citric; CM: citromalic; Fum: fumaric (Adopted from Xie et al., 2022) 8 Strategies to Enhance Pitaya Flavor and Nutritional Quality 8.1 Variety breeding Variety breeding has shown significant progress in improving the sugar and organic acid content of pitaya, which are crucial for its flavor and nutritional quality. Research has identified key genes involved in sugar and organic acid metabolism, such as those encoding for sucrose-hydrolyzing enzymes and sugar transporters. For instance, the expression of genes like HpSuSy1 and HpINV2 has been linked to increased glucose and fructose levels in pitaya (Wei et al., 2019; Mou et al., 2022; Xie et al., 2022). Additionally, the identification of transcription factors such as HpDof1.7, HpDof5.4, and HpWRKY3, which regulate these metabolic pathways, provides new avenues for breeding programs aimed at enhancing fruit sweetness and overall quality (Wei et al., 2019; Mou et al., 2022). The development of new pitaya cultivars with optimized sugar and organic acid profiles can significantly improve the fruit's taste and consumer appeal (Constantino et al., 2021). 8.2 Cultivation management techniques Cultivation management techniques play a pivotal role in regulating sugar and organic acid metabolism in pitaya. Fertilization, irrigation, light exposure, and temperature control are critical factors that influence these metabolic processes. For example, studies have found that the application of potassium fertilizer increased pitaya yield and improved fruit quality, particularly by enhancing the sugar-acid ratio and soluble solids content, indicating that potassium plays a promotive role in sugar and acid metabolism (Fernandes et al., 2018). The combination of organic and inorganic fertilizers significantly improved the sugar-acid ratio and soluble sugar content in pitaya, further highlighting the critical role of fertilization methods in regulating sugar and acid metabolism (de Jesus et al., 2022). Moreover, The use of methyl jasmonate (MeJA) as a pre-treatment has been found to maintain ascorbic acid and organic acid levels while enhancing phenolic accumulation, which contributes to the fruit's nutritional quality and flavor (Li et al., 2018; Serna-Escolano et al., 2020). Effective management of these cultivation parameters can lead to improved sugar and organic acid balance, thereby enhancing the overall quality of pitaya fruits.
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